Intake silencer for gas turbine

ABSTRACT

An intake silencer of a gas turbine capable of efficient noise reduction in which a high frequency sound-absorbing splitter group composed of a plurality of sound-absorbing splitters capable of reducing highfrequency component noise and a middle/low sound-absorbing splitter group composed of a plurality of sound-absorbing splitters capable of reducing middle/low frequency component noise are disposed separately in a gas flow direction. High frequency component noise is reduced by the high frequency sound-absorbing splitter group, and middle/low frequency component noise is reduced by the middle/low sound-absorbing splitter group.

TECHNICAL FIELD

The present invention relates to an intake silencer for a gas turbine.In particular, the present invention relates to an intake silencer for agas turbine capable of successfully reducing intake noise.

BACKGROUND ART

An intake silencer for a gas turbine has been known since the past(refer to, for example, Patent Gazette 1), in which the intake silenceris disposed in a sealed flow path of the intake side of a gas turbine,and is configured by a sound-absorbing splitter group in which aplurality of panel-shaped sound-absorbing splitters including asound-absorbing material therein is disposed in parallel along a gasflow direction.

Conventionally, an intake silencer used in a large gas turbinespecifically has a noise reduction structure configured by a unitarysound-absorbing splitter in which only steel sound-absorbing splitterswith a thickness of 200 millimeters are disposed in parallel along a gasflow direction. Because the sound-absorbing splitter with a thickness of200 millimeters reduces noise mainly at frequencies from 500 Hz to 1 kHzthat do not match the dominant frequency 2 kHz of the gas turbine intakenoise, noise cannot be efficiently reduced.

Moreover, when a required amount of noise reduction is increased, thelength of the sound-absorbing splitter is increased to reduce thedominant frequency 2 kHz of the gas turbine intake noise. As a result ofthe length of the sound-absorbing splitter being increased, noise atfrequencies 1 kHz and below that does not require a very large amount ofreduction is unnecessarily reduced, causing needless noise reduction.

As described above, the conventional intake silencer has disadvantages,in that noise reduction efficiency is poor because of the mismatch innoise frequencies to be reduced, size is increased as a result of thelength simply being increased based on the amount of noise reduction,and the intake silencer is heavy because the entire splitter is made ofsteel.

The main components of the intake noise generated from the gas turbineare a fundamental frequency generated by the rotation of a compressor inthe gas turbine and its overtones. These frequencies are dominantcompared to other frequencies. The fundamental frequency is determinedby the rotation frequency multiplied by the number of blades. In the gasturbine, the rotation frequency is high and the number of blades islarge. Therefore, the fundamental frequency is a high frequency (forexample, 3600(rpm)×36(blades)/60=2160(Hz)).

The intake noise generated at the suction opening of the gas turbinediffers depending on the type and capacity of the gas turbine. However,an approximate noise level within a duct is from 120 dB(A) to 130 dB(A).

As many equipments of the gas turbine are installed outdoor, theacceptable noise level for areas surrounding the equipments is 85 dB (A)in terms of working environment, so the intake silencer is required toreduce a large amount of noise, from 35 dB(A) to 45 dB(A).

Patent Gazette 1: Japanese Patent Laid-open Publication No. 2004-28107

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

The intake noise generated from the suction opening of the gas turbinehas a frequency characteristic in which high frequencies, mainly afundamental frequency 2 kHz and its overtone and half overtone, 4 kHzand 1 kHz, are dominant.

The gas turbine was originally developed in Europe and the UnitedStates. Domestic gas turbines were put into practical use based on thebasic technologies of the original gas turbine.

The same applies to the intake silencer. The structure of theconventional intake silencer is an imitation of the structure used inEurope and the United States. As described above, the conventionalintake silencer has a unitary sound-absorbing splitter noise reductionstructure of steel in which sound-absorbing splitters having a thicknessof 200 millimeters are disposed in parallel along the gas flowdirection.

The conventional intake silencer for a gas turbine will be describedwith reference to FIG. 5.

In FIG. 5, a plurality of panel-shaped sound-absorbing splitters 3, 3 isdisposed in parallel along a gas flow direction indicated by a thickarrow, on a downstream side of an intake filter chamber F in the gasflow direction, within a sealed flow path blocked from its periphery bya duct 1 on an intake side of a gas turbine. Each sound-absorbingsplitter 3 has a steel outer peripheral wall 4 forming a roughrectangular panel. Numerous through holes (not shown) are formed on eachof two mutually opposing side plates 4A and 4B of the outer peripheralwall 4. The interior of the outer peripheral wall 4 is filled with asound-absorbing material (not shown), such as a glass wool board. Theouter peripheral wall 4 is fixed by welding or by a plurality of rivets(not shown).

Moreover, steel tapered frame members 5A and 5B are attached to a frontend section and a rear end section of the outer peripheral wall 4, eachframe member 5A and 5B forming a triangle from a planar view. Thetapered frame members 5A and 5B straighten gas flow passing through thesplitter.

A length of the sound-absorbing splitter 3 in the gas flow direction isabout 4.8 meters. A width of the sound-absorbing splitter 3 is about 20centimeters. Moreover, a distance between a pair of adjacentsound-absorbing splitters 3 and 3 is about 20 centimeters.

Noise reduction effects of a conventional intake silencer of a gasturbine such as this will be described with reference to a graph in FIG.6.

As indicated by a line A in FIG. 6, the power level of the noisegenerated in the gas turbine is a maximum of under 150 dB (A) at thedominant frequency 2 kHz.

On the other hand, as indicated by a line B in FIG. 6, the noise at thefront of the intake filter before installation of the intake silencer isa maximum of under 120 dB (A) at the dominant frequency 2 kHz.

As indicated by a line C in FIG. 6, the noise at the front of the intakefilter in the intake filter chamber F after installation of the intakesilencer is reduced to 50 dB(A) at the frequency 500 Hz. However, thenoise is merely reduced to over 80 dB(A) at the frequency 4 kHz. Thenoise is not sufficiently reduced over the overall frequency range.

In other words, the conventional sound-absorbing splitter 3, describedabove, mainly reduces the frequencies 500 Hz to 1 kHz that do not matchthe dominant frequency 2 kHz of the gas turbine intake noise. Therefore,the noise cannot be efficiently reduced.

Moreover, in response to an increase in the required amount of noisereduction, the sound-absorbing splitter 3 is simply lengthened to alength allowing reduction of noise at a high frequency range centeringon the frequency 2 kHz that is a characteristic of the gas turbineintake noise.

However, as described above, lengthening the sound-absorbing splitter 3causes needless noise reduction in that the noise at a low frequencyrange (1 kHz and below) that does not require a very large amount ofreduction is unnecessarily reduced.

As described above, in the conventional intake silencer, thesound-absorbing splitter has a unitary structure. Therefore, problemsoccur in that noise reduction efficiency is poor because of the mismatchin noise frequencies to be reduced, size is increased as a result of thelength simply being increased based on the amount of noise reduction,and the intake silencer is heavy because the entire splitter is made ofsteel.

Therefore, an object of the present invention is to provide an intakesilencer for a gas turbine capable of efficient noise reduction.

Means for Solving Problem

To achieve the above-described object, an intake silencer of a gasturbine according to a first aspect of the present invention is anintake silencer for a gas turbine disposed on a sealed flow path on anintake side of a gas turbine and configured by a sound-absorbingsplitter group composed of a plurality of panel-shaped sound-absorbingsplitters including a sound-absorbing material therein disposed inparallel along a gas flow direction. In the intake silencer of a gasturbine, a high frequency sound-absorbing splitter group composed of aplurality of sound-absorbing splitters capable of reducing highfrequency component noise and a middle/low frequency sound-absorbingsplitter group composed of a plurality of sound-absorbing splitterscapable of reducing middle/low frequency component noise is disposedseparately in the gas flow direction. As a result of a configurationsuch as this, high frequency component noise can be reduced by the highfrequency sound-absorbing splitter group. Middle/low frequency componentnoise can be reduced by the middle/low sound-absorbing splitter group.

In an intake silencer of a gas turbine according to a second aspect ofthe present invention, the high frequency sound-absorbing splitter groupis disposed on an upstream side in the gas flow direction, and themiddle/low sound-absorbing splitter group is disposed on a downstreamside of the high frequency sound-absorbing splitter group. In an intakesilencer of a gas turbine according to a third aspect of the presentinvention, the middle/low sound-absorbing splitter group is disposed onan upstream side in the gas flow direction, and the high frequencysound-absorbing splitter group is disposed on a downstream side of themiddle/low sound-absorbing splitter group. As a result of aconfiguration such as this, high frequency component noise andmiddle/low frequency component noise can be successfully reducedregardless of which sound-absorbing splitter group is disposed on theupstream side in the flow direction.

In an intake silencer of a gas turbine according to a fourth aspect ofthe present invention, length, width, and interval of eachsound-absorbing splitter configuring the high frequency sound-absorbingsplitter group are each formed shorter than those of eachsound-absorbing splitter configuring the middle/low sound-absorbingsplitter group. As a result of a configuration such as this,characteristics of each sound-absorbing splitter configuring the highfrequency sound-absorbing splitter group and each sound-absorbingsplitter configuring the middle/low sound-absorbing splitter group canbe utilized, thereby successfully reducing high frequency component andmiddle/low frequency component noise.

In an intake silencer of a gas turbine according to a fifth aspect ofthe present invention, each sound-absorbing splitter group is configuredby at least one sound-absorbing splitter block in which a plurality ofsound-absorbing splitters of a same shape is fixed within a rectangulartube-shaped frame. As a result of a configuration such as this,components can be standardized. Cost can be reduced, and processing anddesign can be facilitated.

In an intake silencer of a gas turbine according to a sixth aspect ofthe present invention, a metal portion configuring each sound-absorbingsplitter is formed by corrosion-resistant aluminum. As a result of aconfiguration such as this, weight reduction can be achieved. In anintake silencer of a gas turbine according to a seventh aspect of thepresent invention, a plurality of metal portions configuring eachsound-absorbing splitter is fitted together and fixed. As a result of aconfiguration such as this, the sound-absorbing splitter can beassembled without dependence on the fastening power of rivets.

EFFECT OF THE INVENTION

In the intake silencer of a gas turbine of the present invention, a highfrequency sound-absorbing splitter group composed of a plurality ofsound-absorbing splitters capable of reducing high frequency componentnoise and a middle/low sound-absorbing splitter group composed of aplurality of sound-absorbing splitters capable of reducing middle/lowfrequency component noise are disposed separately in a gas flowdirection. Therefore, high frequency component noise and middle/lowfrequency component noise can be successfully reduced. Moreover,high-frequency component noise and middle/low frequency component noisecan be successfully reduced regardless of which sound-absorbing splittergroup of either the high frequency sound-absorbing splitter group ormiddle/low sound-absorbing splitter group is disposed on the upstreamside in the as flow direction.

In addition, each sound-absorbing splitter configuring the highfrequency sound-absorbing splitter group is formed such that its length,width, and interval are each shorter than those of each sound-absorbingsplitter configuring the middle/low sound-absorbing splitter group.Therefore, the characteristics of each sound-absorbing splitterconfiguring the high frequency sound-absorbing splitter group and eachsound-absorbing splitter configuring the middle/low sound-absorbingsplitter group can be utilized, thereby successfully reducing highfrequency component and middle/low frequency component noise.

In addition, each sound-absorbing splitter group is configured by atleast one sound-absorbing splitter block in which a plurality ofsound-absorbing splitters of a same shape is fixed within a rectangulartube-shaped frame. Therefore, components can be standardized. Cost canbe reduced, and processing and design can be facilitated.

Metal portions configuring each sound-absorbing splitter are formed bycorrosion-resistant aluminum. Therefore, overall weight can be reduced.

In addition, a plurality of metal portions configuring eachsound-absorbing splitter is fitted together and fixed. Therefore, thesound-absorbing splitter can be assembled without dependence on thefastening power of rivets. There is no risk of a rivet flying off anddamaging a blade of the gas turbine and the like.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an intake silencer for a gas turbineaccording to an embodiment of the present invention.

FIG. 2 is a partial perspective view of details of a sound-absorbingsplitter in FIG. 1.

FIG. 3 is a perspective view of a variation example of the embodiment inFIG. 1 in which a sound-absorbing splitter block is used.

FIG. 4 is a graph of noise reduction effects of the intake silencer fora gas turbine according to the embodiment in FIG. 1.

FIG. 5 is a perspective view of a conventional intake silencer for a gasturbine.

FIG. 6 is a graph of noise reduction effects of the intake silencer fora gas turbine in FIG. 5.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a diagram of an intake silencer for a gas turbine according toan embodiment of the present invention. A high frequency sound-absorbingsplitter group 13 is disposed on an upstream side in a gas flowdirection, indicated by a thick outline arrow, on a downstream side ofan intake filter chamber (not shown) in the gas flow direction, within asealed flow path 12 blocked from its periphery by a duct 11 on an intakeside of a gas turbine. The high frequency sound-absorbing splitter group13 is composed of a plurality of sound-absorbing splitters 13A and 13Acapable of reducing high frequency component noise. A middle/lowsound-absorbing splitter group 14 is disposed within the sealed flowpath 12 further on the downstream side in the gas flow direction thanthe high frequency sound-absorbing splitter group 13. The middle/lowsound-absorbing splitter group 14 is composed of a plurality ofsound-absorbing splitters 14A and 14A capable of reducing middle/lowfrequency component noise. Therefore, the high frequency sound-absorbingsplitter group 13 and the middle/low sound-absorbing splitter group 14are disposed separately in the gas flow direction.

As shown in FIG. 2, each sound-absorbing splitter 13A and 14A has acorrosion-resistant aluminum outer peripheral wall 15 forming a roughrectangular panel. Numerous through holes 16 and 16 are formed in analigned state on each of two mutually-opposing side plates 15A and 15Aof the outer peripheral wall 15. The interior of the outer peripheralwall 15 is filled with a sound-absorbing material 17, such as a glasswool, a rock wool, or a polyester board. In FIG. 2, the sound-absorbingmaterial 17 is shown in an exposed state. However, in actuality, theupper surface and the bottom surface of each sound-absorbing splitter13A and 14A are covered by a corrosion-resistant aluminum end plate 15Bhaving a U-shaped cross-section. The end plate 15B is fitted between thetwo side plates 15A and 15A such that the sound-absorbing material 17 isnot exposed.

Moreover, corrosion-resistant aluminum tapered frame members 18 and 18are connected to a front end section and a rear end section of the outerperipheral wall 15. Each frame member 18 and 18 forms a triangle from aplanar view. The tapered frame members 18 and 18 straighten gas flowpassing through the splitter.

In other words, each side plate 15A of the outer peripheral wall 15 isformed having an overall U-shaped cross-section as a result of a bentend plate 19 that is bent to each end surface side. Therefore, a longgroove 20 is formed between the bent end plates 19 and 19 of the twoside plates 15A and 15A, from which the sound-absorbing component 17 isexposed.

On the other hand, two pairs of projections 21A and 21B are disposed ona base section 18A of each tapered frame member 18 such as to project atright angle. The projections 21A and 21B are put in the bent end plate19 of each side plate 15A of the outer peripheral wall 15. As a resultof the pair of projections 21A and 21B being fitted onto both sides ofthe bent end plate 19 of the side plate 15A, the two side plates 15A and15A are held by the two pairs of projections 21A and 21B of each taperedframe member 18. Each side plate 15A is fixed such as to cover thesound-absorbing member 17.

As described above, the plurality of metal portions of eachsound-absorbing splitter 13A and 14A are fixed by being fitted together.The length of each sound-absorbing splitter 13A in the high frequencysound-absorbing splitter group 13 in the gas flow direction is about 40centimeters. The width of each sound-absorbing splitter 13A is about 5centimeters. Moreover, a gap between a pair of adjacent sound-absorbingsplitters 13A and 13A is about 5 centimeters. The length of eachsound-absorbing splitter 14A in the middle/low sound-absorbing splittergroup 14 in the gas flow direction is about 175 centimeters. The widthof each sound-absorbing splitter 14A is about 20 centimeters. Moreover,a gap between a pair of adjacent sound-absorbing splitters 14A and 14Ais about 30 centimeters.

In addition, a gap between each sound-absorbing splitter 13A in the highfrequency sound-absorbing splitter group 13 and each sound-absorbingsplitter 14A in the middle/low sound-absorbing splitter group 14 isabout 25 centimeters.

Similar noise reduction effects can be achieved by the positions of thehigh frequency sound-absorbing splitter group 13 and the middle/lowsound-absorbing splitter group 14 in the gas flow direction beingreversed, such that the middle/low sound-absorbing splitter group 14 isdisposed further upstream than the high frequency sound-absorbingsplitter group 13.

FIG. 3 shows each sound-absorbing splitter group 13 and 14 configuredwith each sound-absorbing splitter 13A and 14A.

In other words, a plurality of sound-absorbing splitters 13A orsound-absorbing splitters 14A having a same shape is disposed at evenintervals and fixed within a rectangular frame 22, thereby forming asound-absorbing splitter block 23. According to the embodiment in FIG.3, the sound-absorbing splitter blocks 23 are assembled three down andtwo across. As a result of the sound-absorbing block 23 being formed inthis way, components can be standardized. Cost can be reduced, andprocessing and design can be facilitated.

Next, effects of the above-described configuration according to theembodiment will be described.

Noise reduction effects of the intake silencer of a gas turbineaccording to the embodiment will be described with reference to a graphin FIG. 4.

As indicated by line A in FIG. 4, the power level of the noise generatedin the gas turbine is a maximum of under 150 dB(A) at the dominantfrequency 2 kHz.

On the other hand, as indicated by line B in FIG. 4, the noise at thefront of the intake filter before installation of the intake silencershows a maximum of under 120 dB(A) at the dominant frequency 2 kHz.

As indicated by line C₁ in FIG. 4, the noise at the front of the intakefilter in the intake filter chamber F after the installation of theintake silencer is first reduced such that the maximum noise is 95 dB(A)at the frequency 500 Hz, as a result of the noise passing through thehigh frequency sound-absorbing splitter group 13 positioned on theupstream side in the gas flow direction. As indicated by line C₂ in FIG.4, the noise is then reduced such that the maximum noise is under 80dB(A) at the frequency 4 kHz, as a result of the noise passing throughthe middle/low sound-absorbing splitter group 14 positioned on thedownstream side in the gas flow direction. At this time, the noise isreduced such that the minimum noise is over 70 dB(A) at the frequency 63Hz.

In other words, in the conventional intake silencer for a gas turbine,noise level after reduction is uneven over the overall frequency range,with a maximum of over 80 dB(A) and a minimum of under 50 dB(A).However, in the intake silencer for a gas turbine according to theembodiment, noise level after reduction is almost even over the overallfrequency range without needless reduction, with a maximum of under 80dB(A) and a minimum of over 70 dB(A). Therefore, noise reduction can besuccessfully performed by the two sound-absorbing splitter groups 13 and14 having an overall shorter length compared to the conventional intakesilencer. Therefore, cost reduction can be achieved within a limitedspace.

According to the embodiment, each sound-absorbing splitter 13A and 14Ais assembled by being fixed simply by a plurality of metal componentsbeing fitted together, rather than being fixed by rivets as in theconvention intake silencer. Therefore, there is no risk of damage to ablade of the gas turbine and the like caused by a rivet becomingdetached and flying off.

Moreover, weight reduction can be achieved because each sound-absorbingsplitter 13A and 14A is formed by corrosion-resistant aluminum. Furtherweight reduction can be achieved by each sound-absorbing splitter 13Aand 14A being formed by hardened plastic instead of corrosion-resistantaluminum.

Furthermore, components can be standardized as a result of thesound-absorbing splitter block 23 being formed in which thesound-absorbing splitters are formed into a block. Cost can be reduced,and processing and design can be facilitated

The present invention is not limited to the above-described embodiments.Various modifications can be made as required. In other words, thedimensions of the sound-absorbing splitters, noise levels, noisefrequencies, and the like are merely examples. The present invention isnot limited by the above-described numbers according to the embodiments.

1. An intake silencer for a gas turbine disposed in a sealed flow pathof an intake of a gas turbine and configured by a sound-absorbingsplitter group composed of a plurality of panel-shaped sound-absorbingsplitters including a sound-absorbing material therein disposed inparallel along a gas flow direction, wherein a high frequencysound-absorbing splitter group composed of a plurality ofsound-absorbing splitters capable of reducing high-frequency componentnoise and a middle/low sound-absorbing splitter group composed of aplurality of sound-absorbing splitters capable of reducing middle/lowfrequency component noise are disposed separately in the gas flowdirection.
 2. The intake silencer for a gas turbine according to claim1, wherein the high frequency sound-absorbing splitter group is disposedon an upstream side in the gas flow direction, and the middle/lowsound-absorbing splitter group is disposed on a downstream side of thehigh frequency sound-absorbing splitter group.
 3. The intake silencerfor a gas turbine according to claim 1, wherein the middle/lowsound-absorbing splitter group is disposed on an upstream side in thegas flow direction, and the high frequency sound-absorbing splittergroup is disposed on a downstream side of the middle/low sound-absorbingsplitter group.
 4. The intake silencer for a gas turbine according toany one of claims 1 to 3, wherein length, width, and interval of eachsound-absorbing splitter configuring the high frequency sound-absorbingsplitter group are each formed shorter than those of eachsound-absorbing splitter configuring the middle/low sound-absorbingsplitter group.
 5. The intake silencer for a gas turbine according toany one of claims 1 to 3, wherein each sound-absorbing splitter group isconfigured by at least one sound-absorbing splitter block in which aplurality of sound-absorbing splitters of a same shape is fixed within arectangular frame.
 6. The intake silencer for a gas turbine according toany one of claims 1 to 3, wherein a metal portion configuring eachsound-absorbing splitter is formed by corrosion-resistant aluminum. 7.The intake silencer for a gas turbine according to any one of claims 1to 3, wherein a plurality of metal portions configuring eachsound-absorbing splitter is fitted together and fixed.